(1) Field of the Invention
The present invention relates to a hemispherical dynamic pressure bearing, and more particularly, to an apparatus for use in a clearance measuring operation for enabling a clearance between a hemisphere and a hemispherical surface of the bearing to be easily measured. The invention also relates to a method of measuring a clearance in a hemispherical dynamic pressure bearing.
(2) Description of Related Art
Generally, a dynamic pressure bearing comprises a supporter, and a rotating member eccentrically and rotatably supported by the supporter. Pressure is formed by a lubricant fluid within a gap defined between the supporter and the rotating member so as to enhance the rotation of the rotating member.
Particularly, a hemispherical type of dynamic bearing is designed such that a portion thereof for supporting the rotating member is hemispherically shaped so as to simultaneously support a radial load and a thrust load.
Referring to FIG. 1, a conventional hemispherical dynamic pressure bearing 9 comprises a supporting shaft 8, and a pair of hemispheres 5 and 6 respectively fixed to upper and lower ends of the supporting shaft 8.
A sleeve 7 is disposed around the supporting shaft 8 between the hemispheres 5 and 6.
A hemispherical bushing 1 includes first and second hemispherical grooves 2 and 3 in which the hemispheres 5 and 6 are disposed, respectively, and a communicating hole 4 for communicating the first and second hemispherical grooves 2 and 3 with each other.
Generally, the hemispheres 5 and 6 are formed through a lapping process, and a light interference measuring system is used to measure a spherical accuracy of the hemispheres.
In addition, a micrometer is further used to measure a clearance between the hemisphere and the hemispherical groove. That is, by using the micrometer, the height of the hemisphere and the depth of the hemispherical groove are measured. Therefore, the value of the clearance can be obtained by a difference between the height and depth.
However, the prior art clearance measuring method as in the above has a drawback in that the measuring process is complicated, resulting in a time-consuming process and an increase in overall manufacturing costs.